1. Field of the Invention
This invention relates to the identification of unknown microorganisms. More particularly, it relates to a method and materials for identification of Neisseria gonorrhoeae by agglutination subsequent to a specific binding reaction between the microorganism and a limited quantity of a specific lectin coated onto a polymeric particle.
2. Description of the Prior Art
The identification of Neisseria gonorrhoeae (N.g.), Neisseria meningitidis (N.m.) and other Neisseria (N.) species in the clinical laboratory is usually accomplished by time consuming culture followed by direct fluorescent antibody detection methods or carbohydrate degradation tests. More rapid carbohydrate degradation tests have been devised which reduce the time required for identification after primary culture by eliminating the requirement for growth during the identification test. In these methods, identification of an isolate is usually achieved after 4 to 5 hours of incubation. Carboyhydrate degradation reactions are generally reliable for the identification of Neisseria species, but there are reports of strains of N.g. and N.m. with aberrant carbohydrate reactions.
D'Amato et al. (J. Clin. Microbiol. 7, 77, (1978)) described the use of chromogenic substances instead of carbohydrate degradation for identification and differentiation of N.g. and N.m. from each other and from other Neisseria species.
Lectins are proteins or glycoproteins of nonimmune origin having two or more binding sites which recognize and bind to specific sugars or sugar sequences present in the cell membranes of most microorganisms, including N.g. Lectin-based agglutination tests which rely on this binding are useful in diagnostic microbiology and represent a significant improvement over costly and labor-intensive agglutination tests using antibodies.
A lectin-specific slide agglutination test for identification of N.g. was disclosed by Schaeffer et al. (J. Clin. Microbiol. 10, 669 (1979) and U.S. Pat. No. 4,389,689) and refined by Doyle et al. (J. Clin. Microbiol. 19, 383 (1984)). This method using wheat germ agglutinin (WGA) was further improved by the modification of Yajko et al. (J. Clin. Microbiol. 19, 380 (1984)) wherein a lectin was combined with a chromogenic substance.
Slifkin et al. (J. Clin. Microbiol. 19, 83 (1984) used a lectin coupled to polystyrene particles as an agglutination reagent for the detection of Group C streptococcal antigen extracts.
A wide variety of lectin kits is marketed by E. Y. Laboratories, Inc., San Mateo, CA, under the trade names Limb.TM., Taxonolectins.TM., and Gonochek.TM.. The Limb.TM. kits are lectins linked to macrobeads. The GONOCHECK kit is directed specifically to identification of N.g.
Despite the improvements in lectin-based microorganism identification described above, unsolved problems still exist. In particular, agglutination of closely related species by a single lectin may reduce assay specificity and cause erroneous results. It is toward the solution of this problem that the present invention is directed.